How to run TypeScript, via ts-node, without ‘experimental’ warnings, and without file extensions on imports

Question

I have a TypeScript project, based on Node.js, with several modules (using workspaces). Everything executes correctly, but I’m still receiving warnings. In particular, when running this (as a package.json ‘script’ in Yarn)

ts-node --project path/tsconfig.json path/script.ts <args-to-script>

I’m seeing two classes of warnings:

• In Visual Studio Code, squiggly underlines in the imports of makefont.ts, because I (have to) specify .ts file extensions;
• At the command-prompt, warning messages on execution, stating that “ExperimentalWarning: Type Stripping is an experimental feature and might change at any time”

I think the two warnings are related. I’m using NodeJS 23.7.0, Yarn 1.22.22, ts-node 10.9.2, TypeScript 5.5.4

Imports with file extensions:

Without the .ts, I get “Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/Users/andrew/projects/retrofabulationzx/app/node_modules/fonts/font1' imported from /Users/andrew/projects/retrofabulationzx/app/rom/build/makefont.ts”

Note that, additionally, I’ve had to split off a type import (Glyph) into a separate import statement. I suspect that both of these issues are related to the ‘Type Stripping’ mentioned below:

ExperimentalWarning

It seems that ts-node is using the (experimental) Node Type Stripping feature to run TypeScript… I am sure that it wasn’t doing this previously, before I implemented workspaces…

Does ts-node have problems running within a Yarn/NPM ‘workspace’?

What the project looks like:

• fonts/ (workspace)
  • font1.ts
  • package.json
  • tsconfig.json
• rom/ (workspace)
  • build/
    • makefont.ts
    • tsconfig.json
  • generated/ (output directory)
  • package.json
• package.json
• tsconfig.json

/package.json

{
    "private": true,
    "workspaces": [
        "fonts",
        "rom",
    ],
    "devDependencies": {
        "@jest/globals": "^29.1.2",
        "@types/node": "^22.4.0",
        "ts-jest": "^29.1.2",
        "ts-node": "^10.9.2",
        "typescript": "^5.5.4"
    },
    "packageManager": "yarn@4.6.0"
}

/tsconfig.json

{
    "compilerOptions": {
        "target": "es6",
        "module": "ES6",
        "outDir": "dist",
        "esModuleInterop": true,
        "moduleResolution": "node"
    },
    "include": [],
    "exclude": [ "**/node_modules" ],
}

fonts/package.json

{
    "name": "fonts",
    "version": "1.0.0",
    "type": "module"
}

fonts/tsconfig.json

{
    "extends": "../tsconfig.json",
    "compilerOptions": {
        "composite": true
    },
    "include": [ "./*.ts" ]
}

rom/package.json

{
    "name": "rom",
    "version": "1.0.0",
    "type": "module",
    "devDependencies": {
        "@types/node": "^22.4.0",
        "fonts": "1.0.0",
        "ts-node": "^10.9.2",
        "typescript": "^5.5.4",
        "zxsys": "1.0.0"
    },
    "scripts": {
        "genfont": "ts-node --project build/tsconfig.json build/makefont.ts generated/font.z80",
        // plus others
    }
}

rom/build/tsconfig.json

{
    "extends": "../../tsconfig.json",
    "ts-node": {
        "esm": true
    },
    "compilerOptions": {
    },
    "references": [
        { "path": "../../fonts" },
        // +others
    ],
    "include": [ "./*.ts" ],
}

Exact command-line invocation

yarn workspace rom genfont